A consecutive series of targeted muscle reinnervation (TMR) cases for relief of neuroma and phantom limb pain: UK perspective.

BACKGROUND: Studies have suggested that targeted muscle reinnervation (TMR) can improve symptoms of neuroma pain (NP) and phantom limb pain (PLP) in patients. OBJECTIVES: Our primary objective was to measure changes in NP and PLP levels following TMR surgery at 4-time points (baseline, 3, 6- and 12-months postoperatively). Secondary aims included identification of the character and rate of any surgical complications and patients' satisfaction with TMR. METHODS: A retrospective review of outcomes of 36 patients who underwent TMR surgery to treat intractable NP and/or PLP after major amputation of an upper (UL) or lower limb (LL) at a single centre in London, UK over 7 years. The surgical techniques, complications, and satisfaction with TMR are described. RESULTS: Forty TMR procedures were performed on 36 patients. Thirty patients had complete data for NP and PLP levels at all pre-defined time points. Significant improvements (p<0.01) in both types of pain were observed for both upper and LL amputees. However, there were varying patterns of recovery. For example, UL amputees experienced worsening of PLP in the first few months post-operatively whereas surgical complications were more common in LL cases. Patients were overwhelmingly satisfied with the improvements in their symptoms (90%). CONCLUSIONS: TMR surgery appeared to relieve both NP and PLP although the retrospective nature of this study limits the strength of this conclusion. However, complication rates were high, and it is crucial for surgeons and patients to fully understand the course and outcomes of this novel surgery prior to undertaking treatment.

Periprosthetic osseointegration fractures are infrequent and management is familiar.

AIMS: Osseointegrated prosthetic limbs allow better mobility than socket-mounted prosthetics for lower limb amputees. Fractures, however, can occur in the residual limb, but they have rarely been reported. Approximately 2% to 3% of amputees with socket-mounted prostheses may fracture within five years. This is the first study which directly addresses the risks and management of periprosthetic osseointegration fractures in amputees. METHODS: A retrospective review identified 518 osseointegration procedures which were undertaken in 458 patients between 2010 and 2018 for whom complete medical records were available. Potential risk factors including time since amputation, age at osseointegration, bone density, weight, uni/bilateral implantation and sex were evaluated with multiple logistic regression. The mechanism of injury, technique and implant that was used for fixation of the fracture, pre-osseointegration and post fracture mobility (assessed using the K-level) and the time that the prosthesis was worn for in hours/day were also assessed. RESULTS: There were 22 periprosthetic fractures; they occurred exclusively in the femur: two in the femoral neck, 14 intertrochanteric and six subtrochanteric, representing 4.2% of 518 osseointegration operations and 6.3% of 347 femoral implants. The vast majority (19/22, 86.4%) occurred within 2 cm of the proximal tip of the implant and after a fall. No fractures occurred spontaneously. Fixation most commonly involved dynamic hip screws (10) and reconstruction plates (9). No osseointegration implants required removal, the K-level was not reduced after fixation of the fracture in any patient, and all retained a K-level of ≥ 2. All fractures united, 21 out of 22 patients (95.5%) wear their osseointegration-mounted prosthetic limb longer daily than when using a socket, with 18 out of 22 (81.8%) reporting using it for ≥ 16 hours daily. Regression analysis identified a 3.89-fold increased risk of fracture for females (p = 0.007) and a 1.02-fold increased risk of fracture per kg above a mean of 80.4 kg (p = 0.046). No increased risk was identified for bilateral implants (p = 0.083), time from amputation to osseointegration (p = 0.974), age at osseointegration (p = 0.331), or bone density (g/cm2, p = 0.560; T-score, p = 0.247; Z-score, p = 0.312). CONCLUSION: The risks and sequelae of periprosthetic fracture after press-fit osseointegration for amputation should not deter patients or clinicians from considering this procedure. Females and heavier patients are likely to have an increased risk of fracture. Age, years since amputation, and bone density do not appear influential. Cite this article: Bone Joint J 2020;102-B(2):162-169.

A Universal Classification System of Skin Substitutes Inspired by Factorial Design.

The complexity of the dermal layer of skin means that damage to this section can result in permanent impairment of function. Partial or total dermal loss is a feature of deep burns and chronic wounds such as pressure sores or diabetic ulcers. The issues posed by traditional skin grafts have led to substantial research being carried out in the fields of tissue engineering and biomaterials science to develop a vast array of alternative skin substitutes. Given the large number of different materials, manufacturing methods, and techniques for implementation described for artificial skin substitutes, many classification systems have been created to simplify their categorization. Some of these systems are oriented toward clinicians while others toward researchers. However, none address the needs of both groups and none are intuitive. The creation of an effective classification system would be particularly helpful in the regulation, distribution, organization, and selection of skin substitutes. The aim of this review is to examine existing methods of classification of skin substitutes, and to propose a new system that uses an algorithm that is inspired by factorial design. Our system allows multiple factors to be simultaneously investigated or in this case, described, since all skin substitutes possess multiple characteristics: (1) cellularity (acellular or cellular), (2) layering (single layer or bilayer), (3) replaced region (epidermis, dermis, or both), (4) materials used (natural, synthetic, or both), and (5) permanence (temporary or permanent). The factors and levels are combined into an algorithm where all the possible combinations are shown. The multifactorial and palindromic structure of our system should enable all users to quickly understand the makeup of a selected skin substitute, or search for a skin substitute depending on their specific requirements. We feel that our proposed classification can be used by clinicians and biomedical researchers alike, which should be an advantage given the multidisciplinary nature of the tissue engineering field and the science that underpins the development of skin substitutes. We also touch upon some of the state-of-the-art skin substitutes that are commercially available or under development to demonstrate how our new method of classification might work.